Bank Angle in the Pattern

[gismo]

I bank it until the stall horn goes off.

I hope you mean "until the horn goes ON". You'd have to roll inverted to get it to go off.

 

[Dan Thomas]

Okay we'll see how well that goes over when there's a parallel runway.

Teach students to SPEED UP if they have to increase bank angle. How to speed up? Get the nose DOWN.

And speeding up increase the turn radius, defeating the higher bank angle anyway.

When we were doing mountain flying, we did minimum-radius turns. The sort of thing one needs to get out of a narrow canyon if the weather ahead is bad or it turns out to be a blind canyon. The technique involved quickly slowing down to 80 MPH (to decrease turn radius), applying 20° flap (this was a 172) to reduce stall speed, cranking into a 60° bank and applying full power in the turn to avoid losing any more airspeed. The turn was amazingly tight and quick. It was also close to the stall, but this was desperation stuff.

Dan

 

[flyingcheesehead]

Okay we'll see how well that goes over when there's a parallel runway.

Teach students to SPEED UP if they have to increase bank angle. How to speed up? Get the nose DOWN. And DESCEND faster.

Yes, you have to learn how to judge if you have enough altitude remaining to do it.

It has zero to do with bank angle. It's about energy and whether or not you have enough of it, or have altitude to trade for it.

Nate, it DOES have to do with bank angle, and many other factors, some of which you mention.

In the parallel-runway situation, I would suggest teaching students to attempt to begin their turns early enough to complete them on centerline with only a 20-degree bank. If it looks like they're not going to make it, they can increase to 30.

As Dan mentioned, speeding up also increases turn radius, so that's not the best solution either. And if you're speeding up in the turn, you're decreasing your load factor which not only accelerates you downward, it also reduces your rate of turn.

 

[denverpilot]

And speeding up increase the turn radius, defeating the higher bank angle anyway.

In level flight, all other things equal.

What's missing from that statement is that in a dive, trading VERTICAL speed to get more energy. Three dimensions.

Yes, you have to pay the piper somewhere, but you did it with altitude.

Think about what happens when a turning horizontal dogfight changes into a vertical one. Now mix them.

You gain something in that first diving turn that you can't get back without lots of engine thrust, an energy assist by gravity. In the dogfight this is bad if the other aircraft has you in thrust to weight. They match your move, turn inside you, and you're dead.

But in the case of turning to line up on something below you, like a runway... with no need to come back up... the added energy of the dive can be utilized to increase the turn rate. Temporarily.

When we were doing mountain flying, we did minimum-radius turns. The sort of thing one needs to get out of a narrow canyon if the weather ahead is bad or it turns out to be a blind canyon. The technique involved quickly slowing down to 80 MPH (to decrease turn radius), applying 20° flap (this was a 172) to reduce stall speed, cranking into a 60° bank and applying full power in the turn to avoid losing any more airspeed. The turn was amazingly tight and quick. It was also close to the stall, but this was desperation stuff.

Yep. I assume 80 MPH is just above a stall in your airplane. I can go much slower in mine.

In that maneuver, you're attempting to maximize turn rate, minimize turn radius, and HOLD altitude. You also in theory have no energy left to go up to slow you're approach to terra firma ahead.

(Think how small a space you'd need to turn around if you had enough thrust to do a hammerhead at that same location as you started your turn at 80 MPH.)

If you can afford to lose altitude you can pull harder after banking and getting the nose down, which will slough the airspeed back to what you are aiming for and make that turn even tighter for the same airspeed (well roughly... stall speed goes up marginally).

Obviously you can't pull to the stall speed you look for in level flight, it's got to be faster.

I'm not recommending HUGE bank angles in the pattern, but somehow students have to at least have this knowledge in their heads and some practice somewhere. If all they know is "20 degrees and maybe 30" as Kent recommends, they don't even have the arrow in their quiver to shoot with -- if they've never seen a safe highly banked turn to final, with the nose considerably below the horizon throughout.

Perhaps the correct introduction is purposely setting up a steep spiral.

Have student transition from steep turn level, to steep turn descending 500 FPM then back to level.

They see what it takes for power and how far down the nose has to be.

This also goes along with Kent's coordination training desire. What does it take to go from level flight to a *coordinated* 45 degree "steep" turn at a constant 500 FPM descent? How much power needed to level that descent off and hold the turn? (Does your airplane have enough? How about on a hot day?) How much does the nose have to pitch down? Why should you NOT try to force it down with inside rudder?

Now try it at 60 degrees. Level steep turn, go to 500 FPM down, level off. (By the way, watch the G's leveling off. It's going to be higher than 2.)

The more I think about it, maybe it's beyond most student level folks. But a Private Pilot with some time in type should be able to do it.

This is only slightly advanced stuff. How to put the airplane where you want it. In three dimensions. It ain't covered by many instructors. It certainly can lead to accidents if the student (no matter their pilot rating) doesn't really understand that you don't get something for nothing.

Kinda like folks not knowing that wings-level on final while high -- a very good technique to come down is just to slow down -- S-turns not always required. Pulling the nose up to the stall horn and then modulating pitch to keep it there, is a perfectly stable way to come down quicker... but that's not taught much either. S-turns are taught.

Just thoughts on aircraft control... The aerobatic folks can chime in here... They get trading that energy for something very well.

Go try it with your "mountain turn". Set up that 80 MPH steep turn and pretend you have 1000 extra feet of altitude. Let the nose fall and pull. Careful not to exceed 3.8 G. But pull to hold 80 and a healthy descent rate at the same time. See if the nose comes around faster. Just get it wings level before pulling out of the resulting dive at first. Don't be over stressing the airplane... After practice you can feel how to roll out as your pull levels you out.

 

[flyingcheesehead]

In level flight, all other things equal.

What's missing from that statement is that in a dive, trading VERTICAL speed to get more energy. Three dimensions.

Yes... But to get that vertical speed in a turn, you're decreasing your load factor which also decreases your rate of turn and increases your turn radius. As I mentioned before, a 45º turn at a load factor of 1 will have the same radius as a 30º turn at a normal load factor (ie vertically steady-state) but will increase your vertical speed by over 500 fpm for every second you hold it that way. Turning base to final at 400 feet and starting at 500 fpm down, you'd be a smoking hole in just slightly over 6 seconds.

So, it sounds like what you're advocating is a high-banked turn with the nose dropping building vertical speed and a quick pull-out? You'd have to reduce bank angle first to avoid a stall on the pull-out, since by definition your vertical acceleration will have to go positive to arrest your descent, meaning a load factor higher than what a level turn would be at the same bank angle. To avoid a stall, that means you'd have to decrease the bank angle.

Realistically, you'd only have about 2 seconds at the 45º angle and 1 g before you'd need to start leveling out and pulling harder, and that 2 seconds will only get you about 1/4 of the way around the base-to-final turn. The rest of the turn then must have both a decreased bank angle AND a higher speed, both of which will increase the radius of the turn... So this is not the solution.

But in the case of turning to line up on something below you, like a runway... with no need to come back up... the added energy of the dive can be utilized to increase the turn rate. Temporarily.

Added speed *lowers* turn rate and *increases* turn radius at the same bank angle. Thus, you have to counteract those effects with an increased bank angle... See where this is going?

Yep. I assume 80 MPH is just above a stall in your airplane. I can go much slower in mine.

The mountain turn speed is different for every plane. However, even with the R/STOL your clean stall speed is roughly the same as a stock 182, right? It's the massive flap/flaperon combo that lets you really slow down, isn't it?

Either way, I think we're talking about the training stall/spin scenario, where a regular old 172 is likely to be involved.

In that maneuver, you're attempting to maximize turn rate, minimize turn radius, and HOLD altitude. You also in theory have no energy left to go up to slow you're approach to terra firma ahead.

Two things maximize turn rate and minimize turn radius: Increased bank angles and slower speeds. Both put us closer to the stall.

I once made a spreadsheet (Who, me? I never do that! ) that calculated turn radius based on bank angle and speed - The smallest possible turn is at 74º bank and right at the stall. That does, however, put you right at the normal category limit load factor so don't f up or you'll pull your wings off. A 61-degree turn will only increase the radius by 10% and will reduce the stall speed by 27 knots (on the 182), while a 45-degree turn will increase the radius by about 35% and reduce stall speed by 41 knots.

Anyway... Back to the situation at hand, while we don't need to hold altitude, we do need to keep our vertical speed from becoming excessive. Since we're already descending before the turn begins, we don't have a huge margin there.

(Think how small a space you'd need to turn around if you had enough thrust to do a hammerhead at that same location as you started your turn at 80 MPH.)

Dare you to fly over the runway downwind and do a split-S to land.

If you can afford to lose altitude you can pull harder after banking and getting the nose down, which will slough the airspeed back to what you are aiming for and make that turn even tighter for the same airspeed (well roughly... stall speed goes up marginally).

If you pull less and then pull more, you have accomplished nothing.

If you bank to 45º*or more and don't pull, you don't get the rate of turn you're looking for. It's only at bank angles significantly above 45º that you can begin to get a decent turn rate without pulling very hard, and that will result in an unacceptable rate of vertical acceleration.

I'm not recommending HUGE bank angles in the pattern, but somehow students have to at least have this knowledge in their heads and some practice somewhere. If all they know is "20 degrees and maybe 30" as Kent recommends, they don't even have the arrow in their quiver to shoot with -- if they've never seen a safe highly banked turn to final, with the nose considerably below the horizon throughout.

I don't think there is such a thing as a "safe highly banked turn to final" for a student pilot.

This also goes along with Kent's coordination training desire. What does it take to go from level flight to a *coordinated* 45 degree "steep" turn at a constant 500 FPM descent? How much power needed to level that descent off and hold the turn? (Does your airplane have enough? How about on a hot day?) How much does the nose have to pitch down? Why should you NOT try to force it down with inside rudder?

Now try it at 60 degrees. Level steep turn, go to 500 FPM down, level off. (By the way, watch the G's leveling off. It's going to be higher than 2.)

I'd love to see you try these maneuvers, Nate... I think they're harder than you think they are.

The more I think about it, maybe it's beyond most student level folks. But a Private Pilot with some time in type should be able to do it.

Now you're getting my problem with what's been said in this thread. We're talking about something that is routinely taught to pre-solo student pilots, but the solutions being offered aren't something that we can reasonably expect students to be able to do safely.

Kinda like folks not knowing that wings-level on final while high -- a very good technique to come down is just to slow down -- S-turns not always required. Pulling the nose up to the stall horn and then modulating pitch to keep it there, is a perfectly stable way to come down quicker... but that's not taught much either. S-turns are taught.

Again, because at the level of a student, S-turns are a much safer maneuver than having them sit right on the edge of the stall while under 1000 AGL.

 

[denverpilot]

Yes... But to get that vertical speed in a turn, you're decreasing your load factor which also decreases your rate of turn and increases your turn radius. As I mentioned before, a 45º turn at a load factor of 1 will have the same radius as a 30º turn at a normal load factor (ie vertically steady-state) but will increase your vertical speed by over 500 fpm for every second you hold it that way. Turning base to final at 400 feet and starting at 500 fpm down, you'd be a smoking hole in just slightly over 6 seconds.

I don't have a darn clue how to do the math, but how does a 45 degree banked turn at a load factor of 2 compare to a 30 degree banked turn at a load factor of 1? (I'd actually like to know how to determine this, but I doubt I can do the math, and it's not exactly in any charts in a POH.)

So, it sounds like what you're advocating is a high-banked turn with the nose dropping building vertical speed and a quick pull-out?

No. You're well above stall speed when you start from a downwind, I'm saying bank hard, pull (higher than 1 load factor), and as speed bleeds down and simultaneously let the nose fall to keep the speed up and the distance traveled laterally shorter during the initial pull. There's probably also an implied power change here, idle the second you roll, and coming back in as speed disappears.

Alternatively, you may even need to slow before banking. Power off, slow to VRef, drop nose and roll in the bank, pull, allow nose to keep coming down to maintain VRef.

The initial pull is slowing you down to a lower speed than the downwind but you stop pulling any harder and start to relax it even, after you've used up that speed.

You'd have to reduce bank angle first to avoid a stall on the pull-out, since by definition your vertical acceleration will have to go positive to arrest your descent, meaning a load factor higher than what a level turn would be at the same bank angle. To avoid a stall, that means you'd have to decrease the bank angle.

You also have power that can be utilized. But yes, there's a smooth continuous return to level flight while continuing to pull.

Realistically, you'd only have about 2 seconds at the 45º angle and 1 g before you'd need to start leveling out and pulling harder, and that 2 seconds will only get you about 1/4 of the way around the base-to-final turn. The rest of the turn then must have both a decreased bank angle AND a higher speed, both of which will increase the radius of the turn... So this is not the solution.

The mistake in your view of what I'm describing is that it's a constant 1G maneuver. Of course, it can't be.

Added speed *lowers* turn rate and *increases* turn radius at the same bank angle. Thus, you have to counteract those effects with an increased bank angle... See where this is going?

At a constant load factor. And not accelerating or decelerating.

The mountain turn speed is different for every plane. However, even with the R/STOL your clean stall speed is roughly the same as a stock 182, right? It's the massive flap/flaperon combo that lets you really slow down, isn't it?

Most places teach it as flaps 20, and pull until the edge of the stall horn but no further. Modulate to turn horn off, pull a little more to turn horn on, repeat, all the way around the corner. (Or just note the indicated airspeed when the horn activates and hold it no matter what and don't change a thing from that point until the turn is completed.)

Throwing the mountain turn in is going to muddy the waters without adding the ability to lose altitude. So let's set this up by using the mountain turn described above.

You bank, hold airspeed, and turn. You add full power if necessary to hold altitude. What was your rate of turn?

Now do the exact same thing but don't add power. If you need more airspeed allow the airplane to descend. What was your rate of turn? Same, right?

Now add power in that descending turn and use it to pull harder. Yes, you can overdo this and get into an accelerated stall. Don't pull so hard indicated airspeed drops any further than before but up the G load in the turn. Pull. What was the turn radius for that one?

Okay... Snipped some stuff out... 'Cause below I see we are saying the same thing...

I once made a spreadsheet (Who, me? I never do that! ) that calculated turn radius based on bank angle and speed - The smallest possible turn is at 74º bank and right at the stall. That does, however, put you right at the normal category limit load factor so don't f up or you'll pull your wings off. A 61-degree turn will only increase the radius by 10% and will reduce the stall speed by 27 knots (on the 182), while a 45-degree turn will increase the radius by about 35% and reduce stall speed by 41 knots.

There you go. I think you meant it would increase stall speed 27 knots, right?

So, get it over to 60 and get it around the corner! Just use power and altitude to not allow that airspeed below Vso+27.

Anyway... Back to the situation at hand, while we don't need to hold altitude, we do need to keep our vertical speed from becoming excessive. Since we're already descending before the turn begins, we don't have a huge margin there.

I was coming at it from the downwind, but you're on base... Ok... That does change things a bit. You really gotta judge sooner than base if you're going to need the higher bank angles to pull it off... and the speed of the downwind and altitude to trade for it. Perhaps that's where we are crossed up a bit. It's a lot less touchy from 1000' AGL going VRef+20 (or so) than at 500' going VRef+10. Agreed.

Dare you to fly over the runway downwind and do a split-S to land.

You joke, but that'd have the smallest turn radius horizontally of anything, if you had the altitude for the vertical "turn". But you need a LOT of power at the bottom, even for a 3.8G pullout.

If you pull less and then pull more, you have accomplished nothing.

Fair enough. Keep pulling. Add power. Heh.

If you bank to 45º*or more and don't pull, you don't get the rate of turn you're looking for. It's only at bank angles significantly above 45º that you can begin to get a decent turn rate without pulling very hard, and that will result in an unacceptable rate of vertical acceleration.

Fair enough. Go to 59. (Joking here because 60 would be "aerobatic" and someone with a protractor and a video camera would bust you. Haha.)

I don't think there is such a thing as a "safe highly banked turn to final" for a student pilot.

You're probably right. In fact I know you're right. They haven't seen nor have any experience at 60.

I'd love to see you try these maneuvers, Nate... I think they're harder than you think they are.

Challenge accepted? Heh. I was already planning on seeing how it'd work out in the practice area. Transitioning from 45 level to 45 down 500 FPM shouldn't be hard. Leveling it out will probably be slightly uncomfortable. In the case of a landing the bank would be removed crisply toward the end, which isn't this maneuver, but that could be done also.

Doing this at 60, very uncomfortable at the level off. Maybe too easy to hit load limit.

A GPS tracker along would be very interesting. I'd like to see just how small a turn radius could be done level, at some reasonable speed like onset of stall horn, no slower... and then add the descent and see how that works out. I'm willing to learn. Always need a good excuse for steep turns, and flying them level doesn't teach me anything new at this point, but would make a nice benchmark on a GPS track. This may be a great "mission" for the next flight.

Now you're getting my problem with what's been said in this thread. We're talking about something that is routinely taught to pre-solo student pilots, but the solutions being offered aren't something that we can reasonably expect students to be able to do safely.

Yeah, I've come around on that point. You're right, students shouldn't be attempting this stuff, but there's a point where a Private Pilot should. Pre-checkride with an instructor would be nice. Spin training pre-checkride would be nice too, but that is long gone... So we hope folks go pick this stuff up later? How many rated Private Pilots have done a spin? How many have done upset training or aerobatics? I just worry a bit that there's no depth to our flying anymore... No attempt to make it 3-dimensional beyond 500 FPM and holding altitude in a 45 degree bank.

Maybe that's really where I'm bummed. My PRIMARY CFI showed me that there was a world beyond 30 degrees of bank and 500 FPM descents. This was while I was a STUDENT. He also explained how it related to flying in the pattern and just how much margin you have in a normal pattern. We did stuff like simulate a base to final turn at altitude all the way to a spin break... heck, we spun out of one even, so I could see how much altitude I was BELOW the simulated runway afterward.

I fear today, someone would say that CFI was "wasting time" or that I "wasn't getting my money's worth" because of the higher than ever costs and the huge focus on hammering things out in 40 hours. Students never get to hear the airspeed dropping toward the spin break. Never get to feel how sloppy the controls get right as a Skyhawk goes over. Never see any of the screaming easy to spot warning signs. Never get to feel the controls get UN-sloppy as the rudder stops the spin.

Stuff like that. I think that stuff was immensely important back then in those early days. My eyeballs and ears matched. We did the stuff multiple times. I had time to get over the overwhelming sensations and study the airspeed indicator as the controls started to feel sloppy. Lots of things come together as a cohesive package.

"Okay, we are 4000' AGL. The airport is 1000 feet below us and abeam you right now. I want you to start a steep turn of more than 45 degrees of bank and less than 60 and descend such that you roll out wings-level 1000' lower and 180 degrees opposite direction. And I want you to decelerate to just getnthe stall horn to come on somewhere in the turn. Go."

Again, because at the level of a student, S-turns are a much safer maneuver than having them sit right on the edge of the stall while under 1000 AGL.

Shallow ones. They get worried and make them steep and they're upping that stall speed you were so worried about. Same difference then. Unless... They put the nose way down. I'm definitely not arguing for that over just pulling the nose up -- if they're past knowing what slow flight looks like and how to maintain it. If they've seen steep turns with a descent (unlikely... Who teaches those?) they'd be okay.

Lets throw out here that this is all Internet Board BS in many ways and the damned best option always is just to go around and set it all up again.

My worry is that, lets call 'em "well beyond solo" students prepping for a Private Ride -- and even many Private rated folks, haven't seen even a level 60 degree steep turn. It's all very Instructor-dependent and not in the PTS. And I think NOT having seen something closer to max performance of the aircraft is doing a lot of people a disservice. They panic at stuff like a 45 degree banked turn and it scares them. Rightly so. If you scare yourself, stop. Always.

Who here had seen 3Gs in a standard spam can before their Provite checkride? Who here hasn't seen it even after and has been flying for years? I'll put myself in that group. The aircraft is rated to 3.8. I've probably bobbled an occasional 60 degree banked level steep turn and pushed it to 2.3 maybe? Max? And I'm already relaxing the back pressure and getting the overbank out that caused it by then? It's pretty darn hard to pull hard enough for non-aerobatic pilots to see 3. We have no idea what our little spamcans are capable of, so we worry at 30 degrees of bank and right above the stall. And if we're only 500' AGL, rightly so... but when we need max performance, we are completely unprepared mentally.

Those of us who grew up with 60 degree (minus one... ha...) steep turns and real spin training have been a little further out the envelope and aren't as worried about the stall horn blipping, wings level, while we can hear plenty of air over that wing... it's not that we're OVER-confident, but we don't panic and start a PIO. Same thing with a blip in a steep turn... It's just not scary. (Have it come in solid, you've probably got our undivided attention and we're pushing forward with yoke, throttle, mixture, and getting that bank out gingerly while still pushing stuff forward with our feet in the panel if we have to. Hahahahaha. Slightly exaggerated, since that is my style, but you know what I mean.)

I guess we try so hard for the airlliner style ride, we forget these winged magic carpets really can do more. That's all I'm realy trying to say.

Folks should grab an instructor who's not scared of so-called "unusual attitudes" and learn exactly what their own chosen spamcan can actually do. It's uncomfortable at first. But you end up a lot less worried about something as begnign as a 45 degree turn from downwind all the way to final while descending at 500 FPM or even 1000. You're just confident the airplane can do it and have seen it before.

Nowadays if you must do that in something aerobatic-rated at high altitudes AGL with an aerobatics Instructor, fine... Go do it if that's what gives you confidence in the ship.

Sorry. Long-winded. I know. Just not sure how to get this point across the best. Old-timers would call this "wringing out the airplane" when they learned a new type. That phrase is even before my time, but it embodies what I'm trying to say that we don't do enough of anymore.

Know the airplane. Know it well at all speeds and attitudes it can accomplish. High bank isn't scary. High bank and low speed at altitude isn't too scary. High bank and low speed at 500 AGL should get your rapt attention... Because you've SEEN it bite you at altitude. You HAVE to see it. Just placing the boogie-man at a particular bank angle or any other number, is fine for student limits. I'm back with you there. But before that Private ticket is in hand, or at least very soon thereafter, find a CFI and see what "heavy" maneuvering looks and feels like in your aircraft. It can do things you don't know it can, and it can do them longer than you'll want to do them!

Okay sorry. Hope that gets the point across. I don't want students dead because they tried to limit bank angle and cheated with bottom rudder. I want them to KNOW what happens when they cheat enough with bottom rudder... Look, the world just went upside down, slowly!

 

[denverpilot]

That last line should have read "when they cheat enough with bottom rudder to CAUSE an upset" at altitude. I re-read it and it sounded very wrong, like they ever should cheat with it.

They should NOT. No. No. No.

But they need to SEE what REALLY happens when they do. Up high.

 

[CMTowner]

I honestly don't pay much attention to the bank angle in the pattern. When I start making turns, I want to get them over as quickly as possible so that I can return to making sure the pattern area is clear. It doesn't matter if I'm flying a C172 or PA28.

 

[Jaybird180]

I honestly don't pay much attention to the bank angle in the pattern. When I start making turns, I want to get them over as quickly as possible so that I can return to making sure the pattern area is clear. It doesn't matter if I'm flying a C172 or PA28.

I think my wife doesn't like that. I tend to snap them over when focusing intently, especially at night retuning from a long XC. I'm working on it.